Friday, January 27, 2017

Finding May Offer Farmers a Way to Reduce Harmful Emissions from Fertilized Soil

Date: January 18, 2017Source: Virginia Institute of Marine ScienceSummary: Production of a potent greenhouse gas can be bypassed as soil nitrogen breaks down into unreactive atmospheric N2, an international team of researchers has discovered.

Those concerned with water quality are familiar with nitrogen as a major pollutant whose excess runoff into coastal waters can lead to algal blooms and low-oxygen dead zones. Perhaps less familiar is the significant role that a form of nitrogen gas plays in greenhouse warming and the destruction of Earth's ozone layer.

Now, an international group of scientists including Dr. B.K. Song of William & Mary's Virginia Institute of Marine Science have discovered that production of this potent greenhouse gas -- known as N2O or nitrous oxide -- can be bypassed as complex nitrogen compounds in soil, water, and fertilizers break down into the unreactive nitrogen gas (N2) that makes up most of our atmosphere.

Their discovery, published in a recent edition of Scientific Reports, reveals an entirely new pathway in the global nitrogen cycle and could lead to new ways for farmers and others to reduce their emissions of harmful gases. The study's lead author is Rebecca Phillips of New Zealand's Landcare Research Institute, along with Landcare colleagues Andrew McMillan, Gwen Grelet, Bevan Weir, and Palmada Thilak; as well as Craig Tobias of the University of Connecticut.

Agriculture contributes more nitrous oxide to the atmosphere than any other human activity -- primarily through nitrogen fertilization. This greenhouse gas is 300 times more effective at trapping heat than carbon dioxide and 10 times more effective than methane. Nitrous oxide also moves into the stratosphere and destroys ozone.

Current wisdom holds that nitrous oxide is inevitably produced when soil nitrogen -- including fertilizer components such as ammonia, ammonium, and urea -- breaks down. It's also thought this breakdown process requires the action of microbes, and can only occur in the absence of oxygen.

The current research contradicts each of these long-held ideas.

"Our findings question the assumption that nitrous oxide is an intermediate required for formation of nitrogen gas [N2]," says Phillips. "They also throw doubt on whether microbial production of nitrous oxide must take place in the absence of oxygen."

"We now have a pathway that doesn't require microbes," adds Song. "The process of denitrification can happen abiotically, without the need for bacteria or fungi."

The team's discovery could lead to practical applications for decreasing the impacts of excess nitrogen in the environment, a topic they focused on while presenting their findings during a recent meeting in Washington D.C. sponsored by the U.S. Department of Agriculture and the National Integrated Water Quality Program.

"It might give us a way to engineer the system to reduce levels of fixed nitrogen," says Song. "By changing the types and ratios of nitrogen compounds in fertilizer, you might have a better way to reduce excess nitrogen, and to mitigate eutrophication or nutrient enrichment in nearby waters."

Phillips adds, "Further research could inform farmers of how to cultivate soil organic matter useful for nitrogen management. Organic forms of soil nitrogen, such as waste products from plants and fungi, could help convert excess inorganic nitrogen -- which would otherwise be leached into water or emitted as nitrous oxide -- into a form that isn't harmful to the environment."

However, the scientists say more research is needed to test exactly which forms of organic nitrogen are most effective. The team is now developing proposals for further funding that will allow them to investigate on-farm applications for transforming excess nitrogen from soil and water into unreactive atmospheric N2 gas without producing N2O. This may allow scientists to develop options to manage the fate of agricultural nitrogen while avoiding greenhouse-gas emissions.

Thursday, January 19, 2017

Date: January 10, 2017Source:University of WaterlooSummary: Upgrades to a wastewater treatment plant along Ontario's Grand River, led to a 70 per cent drop of fish that have both male and female characteristics within one year and a full recovery of the fish population within three years, according to researchers.

PhD candidate Patricija Marjan and Professor Mark Servos collect rainbow darter fish on the Grand River in Ontario.Credit: University of Waterloo

Upgrades to a wastewater treatment plant along Ontario's Grand River led to a 70 per cent drop in fish that have both male and female characteristics within one year and a full recovery of the fish population within three years, according to researchers at the University of Waterloo.

The 10-year study, published in Environmental Science and Technology found that the microorganisms used to remove ammonia in the wastewater treatment process also reduced the levels of endocrine disrupters in the water, which caused the intersex occurrences in fish to dramatically decline.

"Having long-term data of the fish population, before and after the wastewater treatment upgrades makes this a truly unique study," said Mark Servos, Canada Research Chair in Water Quality Protection in Waterloo's Department of Biology. "The changes to Kitchener's wastewater treatment system have had a much larger positive impact then we had anticipated."

In 2007, Servos started tracking the number of intersex male rainbow darter fish in the Grand River. Intersex fish are a result of exposure to natural and synthetic hormones in the water, which cause male fish to grow eggs in their testes. At one point Servos noted the rate of intersex changes in the Grand River was one of the highest in the world.

In 2012, the Region of Waterloo upgraded the Kitchener Wastewater Treatment Plant and changed the aeration tank to reduce toxic ammonia. Within one year the proportion of intersex males dropped from 100 per cent in some areas to 29 per cent. By the end of three years, the numbers dropped below the upstream levels of less than 10 per cent.

"Rainbow darters are the Grand River's canary in the coal mine," said Servos, also a member of the Water Institute at Waterloo. "They're extremely sensitive to the concentration of estrogens and other hormone disrupters in the water. Still, we didn't expect them to recover so quickly."

Endocrine disruption in water systems is a worldwide phenomenon. Estrogen in birth control pills and other chemicals that mimic natural hormones are known to impact fish health in trace amounts as low as one part per trillion, far below what conventional wastewater treatment can typically remove.

"In Europe, water treatment engineers have been turning to extremely expensive tertiary treatments to meet regulatory standards," said Servos. "Kitchener's example shows what can be done with currently available technology."

The Grand River watershed in southern Ontario, is the largest watershed that drains into Lake Erie. The area has a growing population of nearly one million people.

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The American Academy of Environmental Engineering and Scientists is a not-for-profit 501(c)(6) organization serving the Environmental Engineering and Environmental Science professions by providing Board Certification to those who qualify through experience and testing. The Academy also provides training through workshops and seminars, participates in accrediting universities, publishes a periodical and other reference material, interacts with students and young professionals, sponsors a university lecture series, and rewards outstanding achievements through its international awards program.